Keywords in an Array: It can be self-defined. | As for `"key":Object`, *key* is the keyword of *{}* in *"[]":{}*. The type of *Object* is up to *key*.<br /><br />① `"count":Integer`: It's used to count the number. The default largest number is 100. <br /><br />② `"page":Integer`: It’s used for getting data from which page, starting from 0. The default largest number is 100. It’s usually used with COUNT. <br /><br />③ `"query":Integer`: Get the number of items that match conditions<br />When to get the object, the integer should be 0; when to get the total number, it’s 1; when both above, it’s 2.<br />You can get the total number with keyword total. It can be referred to other values. Eg. `"total@":"/[]/total"` Put it as the same level of query. <br />*Query* and *total* are used in GET requests just for convenience. Generally, HEAD request is for getting numbers like the total number.<br /><br />④ "join":"&/Table0/key0@,\</Table1/key1@"<br />Join tables：<br /> "\<" - LEFT JOIN <br /> ">" - RIGHT JOIN <br /> "&" - INNER JOIN <br /> "\|" - FULL JOIN <br /> "!" - OUTTER JOIN <br /> "@" - APP JOIN <br />Where @ APP JOIN is in application layer.It’ll get all the keys in tables that refKeys in result tables are referred to, like refKeys:[value0, value1….]. Then, as the results get data according to `key=$refKey` a number of times (COUNT), it uses key `IN($refKeys)` to put these counts together in just one SQL query, in order to improve the performance.<br /> Other JOIN functions are the same as those in SQL.<br />`“resultTable”:{“key@”: “.../MainTable/refKey”}`<br />will return<br />`Table ... JOIN resultTable ON resultTable.key=Table.refKey` <br /><br />⑤ `"otherKey": Object`: Self-defined keyword other than those that already in the system. It also returns with self-defined keywords.| ① Get User arrays with maximum of 5：<br />["count":5](http://apijson.cn:8080/get/{"[]":{"count":5,"User":{}}})<br /><br /> ② Look into User arrays on page 3. Show 5 of them each page. <br />["count":5,<br />"page":3](http://apijson.cn:8080/get/{"[]":{"count":5,"page":3,"User":{}}})<br /><br /> ③ Get User Arrays and count the total number of Users：<br />["[]":{<br /> &nbsp;&nbsp; "query":2,<br /> &nbsp;&nbsp; "User":{}<br />},<br />"total@":"/[]/total"](http://apijson.cn:8080/get/{"[]":{"query":2,"count":5,"User":{}},"total@":"%252F[]%252Ftotal"})<br />Questions like total page numbers or if there's next page can be solved by total,count,page functions，<br />Total page number: `int totalPage = Math.ceil(total \/ count)`<br />If this is the last page: `boolean hasNextPage = total > count\*page`<br />If this is the first page: `boolean isFirstPage = page <= 0`<br />If it's the last page: `boolean isLastPage = total <= count\*page`<br />... <br /><br /> ④ Moment INNER JOIN User LEFT JOIN Comment：<br />["[]":{<br /> &nbsp;&nbsp; "join": "&/User/id@,\</Comment/momentId@",<br /> &nbsp;&nbsp; "Moment":{},<br /> &nbsp;&nbsp; "User":{<br /> &nbsp;&nbsp;&nbsp;&nbsp; "name~":"t",<br /> &nbsp;&nbsp;&nbsp;&nbsp; "id@": "/Moment/userId"<br /> &nbsp;&nbsp; },<br /> &nbsp;&nbsp; "Comment":{<br /> &nbsp;&nbsp;&nbsp;&nbsp; "momentId@": "/Moment/id"<br /> &nbsp;&nbsp; }<br />}](http://apijson.cn:8080/get/{"[]":{"count":5,"join":"&%252FUser%252Fid@,\<%252FComment%252FmomentId@","Moment":{"@column":"id,userId,content"},"User":{"name~":"t","id@":"%252FMoment%252FuserId","@column":"id,name,head"},"Comment":{"momentId@":"%252FMoment%252Fid","@column":"id,momentId,content"}}})<br /><br /> ⑤ Add the current user to every level：<br />["User":{},<br />"[]":{<br /> &nbsp;&nbsp; "name@":"User/name", //self-defined keyword<br /> &nbsp;&nbsp; "Moment":{}<br />}](http://apijson.cn:8080/get/{"User":{},"[]":{"name@":"User%252Fname","Moment":{}}})

Keywords in Objects: It can be self-defined. | `"@key":Object`:@key is the keyword of {} in Table:{}. The type of Object is decided by @key<br /><br />① `"@combine":"&key0,&key1,\|key2,key3,<br />!key4,!key5,&key6,key7..."`<br >First, it’ll group data with same operators. Within one group, it operates from left to right. Then it’ll follow the order of & \| ! to do the operation. Different groups are connected with &. So the expression above will be : <br /> (key0 & key1 & key6 & other key) & (key2 \| key3 \| key7) & !(key4 \| key5) <br />\| is optional. <br /><br />②` "@column":"column;function(arg)..."` Return with specific columns.<br /><br />③ `"@order":"column0+,column1-..."`: Decide the order of returning results:<br /><br />④ `"@group":"column0,column1..."`:How to group data. If @column has declared Table id, this id need to be included in @group. In other situations, at least one of the following needs to be done:<br />1.Group id is declared in @column<br />2.Primary Key of the table is declared in @group.<br/><br/>⑤`"@having":"function0(...)?value0;function1(...)?value1;function2(...)?value2..."`:Add conditions on return results with @having. Usually working with@group, it’s declared in @column.<br /><br />⑥ `"@schema":"sys"`:Can be set as default setting.<br /><br />⑦ `"@database":"POSTGRESQL"`:Get data from a different database.Can be set as default setting.<br /><br />⑧ `"@role": "OWNER"`:Get information of the user, including <br />UNKNOWN,LOGIN,CONTACT,CIRCLE,OWNER,ADMIN，<br />Can be set as default setting. <br />You can self-define a new role or rewrite a role. Use`Verifier.verify` etc. to self-define validation methods. <br /><br />⑨` "@explain": true` :Profiling. Can be set as default setting. <br /><br />⑩ `"@otherKey": Object`: Self-define keyword | ① Search *Users* that *name* or *tag* contains the letter "a":<br />["name~":"a",<br />"tag~":"a",<br />"@combine":"name~,tag~"](http://apijson.cn:8080/get/{"User[]":{"count":10,"User":{"@column":"id,name,tag","name~":"a","tag~":"a","@combine":"name~,tag~"}}})<br /><br /> ② Only search column id,sex,name and return with the same order:<br />["@column":"id,sex,name"](http://apijson.cn:8080/get/{"User":{"@column":"id,sex,name","id":38710}})<br /><br /> ③ Search Users that have descending order of name and default order of id:<br />["@order":"name-,id"](http://apijson.cn:8080/get/{"[]":{"count":10,"User":{"@column":"name,id","@order":"name-,id"}}})<br /><br /> ④ Search Moment grouped with userId: <br />["@group":"userId,id"](http://apijson.cn:8080/get/{"[]":{"count":10,"Moment":%7B"@column":"userId,id","@group":"userId,id"}}})<br /><br /> ⑤ Search Moments that id equals or less than 100 and group with userId:<br />["@column":"userId;max(id)",<br />"@group":"userId",<br />"@having":"max(id)>=100"](http://apijson.cn:8080/get/{"[]":{"count":10,"Moment":{"@column":"userId%253Bmax(id)","@group":"userId","@having":"max(id)>=100"}}})<br />You can also define the name of the returned function:<br />["@column":"userId;max(id):maxId",<br />"@group":"userId",<br />"@having":"maxId>=100"](http://apijson.cn:8080/get/{"[]":{"count":10,"Moment":{"@column":"userId%253Bmax(id):maxId","@group":"userId","@having":"maxId>=100"}}})<br /><br /> ⑥ Check Users table in sys: <br />["@schema":"sys"](http://apijson.cn:8080/get/{"User":{"@schema":"sys"}})<br /><br /> ⑦ Check Users table in PostgreSQL:<br />["@database":"POSTGRESQL"](http://apijson.cn:8080/get/{"User":{"@database":"POSTGRESQL"}})<br /><br /> ⑧ Check the current user's activity:<br />["@role":"OWNER"](http://apijson.cn:8080/get/{"[]":{"Moment":{"@role":"OWNER"}}})<br /><br /> ⑨ Turn on profiling: <br />["@explain":true](http://apijson.cn:8080/get/{"[]":{"Moment":{"@explain":true}}})<br /><br /> ⑩ Get the No.0 picture from pictureList：<br />["@position":0, //self-defined keyword<br />"firstPicture()":"getFromArray(pictureList,@position)"](http://apijson.cn:8080/get/{"User":{"id":38710,"@position":0,"firstPicture()":"getFromArray(pictureList,@position)"}})